Sound producers



Filed June 29, 1955 fsiii'mf.

,Mrt a i II .9

United States Patent O SOUND PRODUCERS Gustav Zeininger, Oberesslingen,and Jrg Issler, Stuttgart, Germany, assignors to Robert Bosch G. m. b.H., Stuttgart, Germany Application June 29, 1953, Serial No. 364,734

Claims priority, application Germany July 5, 1952 6 Claims. (Cl.340-388) The invention relates to a sound producer having a diaphragmwhich is set vibrating by periodic power impulses and which is connectedcentrally with a substantially even circular vibratory disc, moreparticularly to a signal horn for mechanically propelled vehicles.

With the previously known sound producers of the type set forth thevibratory disc is either equally thick throughout or is tapered towardsits edge.

The effect of a vibratory disc on the strength and audibility of thesound waves emitted may be improved in a surprising manner if it isreinforced in its freely vibrating marginal area in accordance with thepresent invention.

By this means it is rendered possible for as large a portion as possibleof the energy imparted to the vibratory disc by the power impulses to beradiated in the high frequencies whereby sound waves of a toneparticularly suitable for penetrating areas of noise are produced.

Sound producers are also already known in which there is providedinstead of an even circular vibratory disc, a at vibratory beam which istapered in cross section on both sides of a central attachment point inorder to give greater elasticity to both its arms. These vibratory beamshave comparatively accurately defined vibration and depend substantiallyonly on the diaphragm for the formation of the sound waves. Thevibratory disc constructed in accordance with the invention on the otherhand also acts directly as a radiating surface which transmits energy invibrations particularly in the high frequencies.

The invention will be further described by way of example in greaterdetail with reference to the accompanying drawings which show by way ofexample one construction embodying the present invention and in which:

Fig. 1 is a diagrammatic sectional view through an electromagneticallyactuated horn,

Fig. 2 is a front view of the vibratory disc,

Fig. 3 is a cross section on line III--III of Fig. 2, and

Fig. 4 is a view similar to Fig. l and showing the armature impinging onthe core.

An electro-magnet 2 is mounted in a casing 1 and is excited periodicallyin a manner not shown in greater detail. Opposite the poles of theelectro-magnet 2 is disposed an armature 3 which is firmly connectedthereto with a bolt 4. On the bolt are also secured a diaphragm 5 and avibratory disc 6. The diaphragm 5 which is illustrated in the drawing asan even at diaphragm, but could equally well be a diaphragm providedwith annular corrugations, is firmly gripped on its outer peripherybetween a marginal section of the casing 1 and a closing ring 7, theinner edge of which extends into the vicinity of the outer edge of thevibratory disc 6.

On its outer edge, the vibratory disc 6 has a rim-like reinforcement 8which projects out of the plane of the disc on one side. In the exampleof construction illustrated the disc 6 is so mounted that the rim 8 isdisposed on the side of the disc 6 turned away from the diaphragm 5 sothat the disc may be disposed as near as possible to the diaphragm. Theinner edge 9 of the n'm of the disc 2,787,786 Patented Apr. 2, 1957 isinclined in a direction towards the middle of the disc whereby themechanical durability of the disc, as also the formation of thevibration, is improved.

It has proved to be an advantage if the rim 8 `is so proportioned thatits radial width is smaller than one eighth ofthe diameter of the disc6, whilst the axial thickness of the reinforcement 8 is about twice thethickness of the centre part of the disc.

For the desired production of a sound-penetrating tone it is also anadvantage for the diameter of the vibratory disc 6 to be greater thanhalf of the diameter of the vibratory part of the diaphragm 5.

For the vibratory disc 6 special materials with low internal dampingeffect are suitable such as for example aluminium, artificial material,ceramic substances, glass or the like.

The air gap d between the core of the electromagnet 2 and the armature 3connected with the diaphragm when in resting position is so small, thatthe armature impinges on the core on every pull exerted by theelectromagnet as shown in Fig. 4.

We claim:

1. In a sound producer, a diaphragm, means for im parting periodicvibration exciting power impulses to the diaphragm, a vibratory discdisposed in confronting spaced relation to the diaphragm, means forconnecting the center of said disc to the center of the diaphragm, saiddisc having a central portion of substantially uniform thickness andbeing reinforced in thickness in its marginal region.

2. In a sound producer, a diaphragm, means for imparting periodicvibration exciting power impulses to the diaphragm, a vibratory discdisposed in confronting relation to the diaphragm, means for connectingthe center of said disc to the center of the diaphragm, said disc havingan inner portion of substantially uniform thickness and a rim portion ofincreased thickness projecting from the disc in a direction away fromthe diaphragm, said rim portion having an inner surface inclined in adirection towards the center of the disc.

3. In a sound producer, a diaphragm, means for clamping the diaphragm atits marginal edge, means for imparting periodic vibration exciting powerimpulses to the central portion of the diaphragm, a vibratory discdisposed in face to face confronting relation with the diaphragm, meansfor connecting the center of said disc to the -central portion of thediaphragm, 'said disc having a center portion of substantially uniformthickness and a rim portion of increased thickness projecting from thedisc in a direction away from the diaphragm, the disc yhaving a diametergreater than half the diameter of the vibrating center portion of thediaphragm.

4. In a sound producer, a diaphragm, means for imparting periodicvibration exciting power impulses to theydi-aphragm, a vibratory discdisposed in face to face confronting relation with the diaphragm, meansfor connecting the center of said disc lto the diaphragm, said dischaving an inner portion of substantially uniform thickness and a rimportion of increased thickness projecting from the -disc `on only oneside of the disc, the thickness `of the rim of the disc beingapproximately twice the thickness of the inner portion of the disc.

5. In a sound producer having a vibrating diaphragm, a vibratory discdisposed in confronting face to face spaced relation with the diaphragm,means for connecting the center of the disc to the center `of thevibrating diaphragm with `outer parts of the disc free to vibrate, saiddisc having `an inner portion of substantially uniform thickness and arim portion of increased thickness projecting from the disc on only oneside `of the disc, the radial width of the rim of the disc being lessth-an one eighth of the diameter of the disc. V

6. In a sound producer, a disc shaped diaphragm, means for impartingperiodic vibration exciting power impulses to the diaphragm, a vibratorydisc, means for clamping the marginal edge of the diaphragm so that onlythe center portion of the diaphragm can vibrate, means connecting thecenter of the disc to the center of the diaphragm and disposing the disein spaced face to face relation with the diaphragm, said disc having -adiameter greater than half the diameter of the vibrating center portionof the diaphragm, said disc having a center portion of substantiallyuniform thickness and a rim portion having a thickness approximatelytwice the thickness of the inner portion, said rim portion having aradial width less than one eighth of the diameter of the disc,projecting from the disc in a direction away from the diaphragm, andhaving lan inner surface inclined in a direction towards the center ofthe disc.

References Cited in the le of this patent UNITED STATES PATENTS1,523,964 Horig Ian. 20, 1925 1,737,883 Hecht a Dec. 3, 1929 1,940,150Sei'ss Dec. 19, 1933 2,046,772 Critchfield July 7, 1936 2,228,677Scofield Jan. 14, -1941 FOREIGN PATENTS 346,355 Germany Dec, 29, 1952

